Autofecondazione in Asterina.

Abstract

In Asterina, the sperm appears when the eggs come out from the oviducte; moreover it is able to fertilize all the spawned eggs. It is assumed that in A. pancerii this spermatogenetic stage has a true functional meaning; indeed the young spermatogenetic stage is missing together with the partenogenetic development. In free individuals of A. pancerii probably there is not self-fecundation, at least for most of the eggs; the spawning in isolated bred animals of the species occurs indeed at the same hour in groups of individuals. In A. gibbosa the adaptive meaning of the secondary spermatogenesis is probably to be considered as the possibility for isolated individuals to occupy new areas.